linux-kernel - Re: [PATCH] vsprintf: Do not break early boot with probing addresses

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Message-ID: <daf4dfd1-7f4f-8b92-6866-437c3a2be28b@c-s.fr>
Date:   Fri, 10 May 2019 19:35:29 +0200
From:   christophe leroy <christophe.leroy@....fr>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Petr Mladek <pmladek@...e.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>, Michal Hocko <mhocko@...e.cz>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, Russell Currey <ruscur@...sell.cc>,
        Stephen Rothwell <sfr@...abs.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        linux-arch@...r.kernel.org, linux-s390@...r.kernel.org,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: [PATCH] vsprintf: Do not break early boot with probing addresses



Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
> On Fri, 10 May 2019 10:42:13 +0200
> Petr Mladek <pmladek@...e.com> wrote:
> 
>>   static const char *check_pointer_msg(const void *ptr)
>>   {
>> -	char byte;
>> -
>>   	if (!ptr)
>>   		return "(null)";
>>   
>> -	if (probe_kernel_address(ptr, byte))
>> +	if ((unsigned long)ptr < PAGE_SIZE || IS_ERR_VALUE(ptr))
>>   		return "(efault)";
>>   
> 
> 
> 	< PAGE_SIZE ?
> 
> do you mean: < TASK_SIZE ?

I guess not.

Usually, < PAGE_SIZE means NULL pointer dereference (via the member of a 
struct)

Christophe

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